Peat

The biological features of sphagnum mosses act to create a habitat aiding peat formation, a phenomenon termed 'habitat manipulation'.

Peat forms in wetland conditions, where flooding or stagnant water obstructs the flow of oxygen from the atmosphere, slowing the rate of decomposition.

Landscapes covered in peat are home to specific kinds of plants, including Sphagnum moss, ericaceous shrubs and sedges.

[Notes 1] Because organic matter accumulates over thousands of years, peat deposits provide records of past vegetation and climate by preserving plant remains, such as pollen.

[17] Centuries of burning and draining of peat by humans has released a significant amount of CO2 into the atmosphere,[18] and much peatland restoration is needed to help limit climate change.

[citation needed] Most modern peat bogs formed 12,000 years ago in high latitudes after the glaciers retreated at the end of the last ice age.

This soil is problematic because it exhibits poor consolidation properties—it cannot be easily compacted to serve as a stable foundation to support loads, such as roads or buildings.

These ecosystems are characterized by the unique ability to accumulate and store dead organic matter from Sphagnum and many other non-moss species, as peat, under conditions of almost permanent water saturation.

In many countries, including Ireland and Scotland, peat was traditionally stacked to dry in rural areas and used for cooking and domestic heating.

[citation needed] The most essential property of peat is retaining moisture in container soil when it is dry while preventing the excess water from killing roots when it is wet.

[32] While bark or coir-based peat-free potting soil mixes are on the rise, particularly in the UK, peat is still used as raw material for horticulture in some other European countries, Canada, as well as parts of the United States.

[33]Peat wetlands also used to have a degree of metallurgical importance in the Early Middle Ages, being the primary source of bog iron used to create swords and armour.

In addition to being soft and therefore suitable for demersal (bottom-dwelling) species such as Corydoras catfish, peat is reported to have many other beneficial functions in freshwater aquaria.

[38] Authors Rydin and Jeglum in Biology of Habitats described the concept of peat archives, a phrase coined by influential peatland scientist Harry Godwin in 1981.

These remains are collectively termed the peat archives.In Quaternary Palaeoecology, first published in 1980, Birks and Birks described how paleoecological studies "of peat can be used to reveal what plant communities were present (locally and regionally), what period each community occupied, how environmental conditions changed, and how the environment affected the ecosystem in that time and place.

Palsa mires have a rich bird life and are an EU-red listed habitat,[48] and in Canada riparian peat banks are used as maternity sites for polar bears.

[63] Peat fires may burn for great lengths of time, or smoulder underground and reignite after winter if an oxygen source is present.

These smouldering fires can burn undetected for very long periods of time (months, years, and even centuries) propagating in a creeping fashion through the underground peat layer.

Several families of plants including the carnivorous Sarracenia (trumpet pitcher), Dionaea (Venus flytrap), Utricularia (bladderworts) and non-carnivorous plants such as the sandhills lily, toothache grass and many species of orchid are now threatened and in some cases endangered from the combined forces of human drainage, negligence and absence of fire.

In North America, peat fires can occur during severe droughts throughout their occurrence, from boreal forests in Canada to swamps and fens in the subtropical southern Florida Everglades.

[73] In the summer of 2010, an unusually high heat wave of up to 40 °C (104 °F) ignited large deposits of peat in Central Russia, burning thousands of houses and covering the capital of Moscow with a toxic smoke blanket.

[80] In June 2002, the United Nations Development Programme launched the Wetlands Ecosystem and Tropical Peat Swamp Forest Rehabilitation Project.

This publication aims to develop mechanisms that can balance the conflicting demands on the global peatland heritage to ensure its wise use to meet the needs of humankind.

[95] At the same time, restoration of drained peatlands through rewetting is urged by national and international policies to exploit the peat-rich soil properties in mitigating climate change effects.

[citation needed] In January 2021, Bord na Móna announced that it had ceased all peat harvesting and cutting operations and would move its business to a climate solutions company.

Drainage, causing compaction and oxidation and excavation have reduced peatlands (>40 cm [16 in] peat) to about 2,733 km2 (1,055 sq mi)[100] or 10% of the land area, mostly used as meadows.

[116] Recently regeneration of peatland has occurred as part of the Thorne Moors project, and at Fleet Moss, organised by Yorkshire Wildlife Trust.

In response, afforestation has seen the establishment of tentative steps towards conservation such as Peatlands Park, County Armagh which is an Area of Special Scientific Interest.

Because they are easily compressed under minimal weight, peat deposits pose significant difficulties for building structures, roads and railways.

When the West Highland railway line was constructed across Rannoch Moor in western Scotland, its builders had to float the tracks on a multi-thousand-ton mattress of tree roots, brushwood, earth and ash.